Duty Cycle & Pulse Width Modulation (PWM) Meter

For display of ON or OFF period in percent

Duty cycle meter by TD Micronic

Features

  • Takes ratio of ON or OFF period and total period.
  • Displays Duty Cycle with resolution of 1%, 0.1% or 0.01%.
  • Displays Pulse Width Modulation (PWM) in engineering units
  • Triggers on positive or negative pulse edges.
  • Frequencies from 0.005 Hz to 10 kHz.
  • 6-digit red or green LED display.
  • Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac power
  • Transducer excitation output (isolated)
  • Wide choice of options:
    - 2 or 4 relays, mechanical or solid state (isolated)
    - 1 or 2 analog outputs (isolated)
    - Serial data I/O: Ethernet, USB, RS485, RS232 (isolated)
Description
Duty Cycle Meter by TD Micronic

Clock diagram, 4-20 mA duty cycle transmitterDuty cycle is a measure of ON or OFF period as a percentage of total period. Duty cycle is determined by averaging an integral number of periods over a gate time which is selectable from 10 ms to 199.99 s. The same signal is applied to Channels A and B. The meter divides the average pulse width t by the period P between pulses and expresses the ratio t/P in percent. A resolution of 1%, 0.1% or 0.01% is selectable. By selecting leading or falling pulse edges, ON or OFF duty cycle can be displayed.

Pulse Width Modulation (PWM) is a transducer output format where the measured information is provided as duty cycle applied to a constant frequeny, such as 120 Hz. As for duty cycle, the meter divides the average pulse width by the period between pulses over a gate time which is selectable from 10 ms to 199.99 s. It then scales this ratio mathematically to display this ratio in engineering units, such as relative humidity (RH).

RTD signal conditioner boardThe duty cycle & pulse width modulation meter uses an Extended counter main board and the FR dual-channel signal conditioner board, which accepts signals from 12 mV to 250 Vac, inputs from proximity switches with a PNP or NPN output, TTL or CMOS logic, and contact closures. Jumper selections provide optimum operation for different sensor types and noise conditions. A built-in isolated 5, 10, or 24 Vdc excitation supply can power proximity switches and other sensors.

Designed for system use. Optional plug-in boards for communications and control include Ethernet and other serial communication boards, dual or quad relay boards, and an isolated analog output board. s may be powered from 85-264 Vac or optionally from 12-32 Vac or 10-48 Vdc. The display is available with red or green LEDs. The 1/8 DIN case meets NEMA 4X (IP65) specifications from the front when panel mounted. Any setup functions and front panel keys can be locked out for simplified usage and security. All power and signal connections are via UL / VDE / CSA rated screw clamp plugs.

Specifications
Duty Cycle Measurement
Item Displayed ON or OFF duty cycle of periodic pulse waveshape
Display Units 1%, 0.1%, 0.01%
Frequency Range 0.005 Hz to 10 kHz
Accuracy 0.01%, 0.005 Hz to 500 Hz, 0.1% at 5 kHz, 1% at 10 kHz
Maximum Timing Interval 199.99 s
Pulse Width Modulation (PWM) Measurement
Item Displayed Measurement based on Pulse Width Modulation (PWM) input
Display Units Scaled reading in engineering units
Frequency Range 0.005 Hz to 10 kHz
Accuracy 0.01%, 0.005 Hz to 500 Hz, 0.1% at 5 kHz, 1% at 10 kHz
Maximum Timing Interval 199.99 s
Display
Readout 6 LED digits, 7-segment, 14.2 mm (.56"), red or green.
Range -999999 to +999999
Indicators Four LED lamps
Inputs
Types AC, pulses from NPN, PNP transistors, contact closures, magnetic pickups.
Signal Ground Common ground for channels A & B
Minimum Signal Nine ranges from (-12 to +12 mV) to (+1.25 to +2.1V).
Maximum Signal 250 Vac
Noise Filter 1 MHz, 30 kHz, 250 Hz (selectable)
Contact Debounce 0, 3, 50 ms (selectable)
Update Rate
Conversion Interval Gate time + 30 ms+ 0-2 signal periods
Gate Time Selectable 10 ms to 199.99 s
Time Before Zero Out Selectable 10 ms to 199.99 s
Power
Voltage, standard 85-264 Vac or 90-300 Vdc
Voltage, optional 12-32 Vac or 10-48 Vdc
Frequency DC or 47-63 Hz
Power  consumption (typical, base meter) 1.2W @ 120 Vac, 1.5W @ 240 Vac, 1.3W @ 10 Vdc, 1.4W @ 20 Vdc, 1.55W @ 30 Vdc, 1.8W @ 40 Vdc, 2.15W @ 48 Vdc
Power Isolation 250V rms working, 2.3 kV rms per 1 min test
Analog Output (optional)
Output levels 4-20 mA, 0-20 mA, 0-10V, -10 to +10V (jumper selectable)
Current compliance 2 mA at 10V ( > 5 kΩ load)
Voltage compliance 12V at 20 mA (< 600Ω load)
Scaling Zero and full scale adjustable from -99999 to +99999
Resolution 16 bits (0.0015% of full scale)
Isolation 250V rms working, 2.3 kV rms per 1 min test
(dual analog outputs share the same ground)
(optional)
Relay types 2 Form C contact relays or 4 Form A contact relays (NO) 2 or 4 Form A, AC/DC solid state relays (NO)
Current Ratings 8A at 250 Vac or 24 Vdc for contact relays 120 mA at 140 Vac or 180 Vdc for solid state relays
Output common Isolated commons for dual relays or each pair of quad relays
Isolation 250V rms working, 2.3 kV rms per 1 min tes
Serial Data I/O (optional)
Board selections RS232, RS485 (dual RJ11 or RJ45 connectors), USB,Ethernet, USB-to-RS485 converter, Ethernet-to-RS485 converter
Protocols Modbus RTU, Modbus ASCII, Modbus TCP (Ethernet), TDM ASCII
Data rates 300 to 19200 baud
Digital addresses 247 (Modbus), 31 (TDM ASCII),
Isolation 250V rms working, 2.3 kV rms per 1 min test
Environmental
Operating temperature 0°C to 55°C
Storage temperature. -40°C to 85°C
Relative humidity 95% at 40°C, non-condensing
Protection NEMA-4X (IP-65) when panel mounted
Signal Connections
Duty Cycle Flow Graph
Applications
Duty Cycle & Pulse Width Modulation (PWM) Modes
Duty cycle graphr In duty cycle mode, the meter displays ON or OFF time in percent from 0% to 100% of period for repetitive pulse trains. In the illustration, duty cycle in percent is 100 x t/P. In pulse width modulation (PWM) mode, the meter also determines the duty cycle ratio, but then scales this ratio for display in engineering units.
Monitoring Laser OperationPM and Speed
Duty cycle measurement counters can be programmed to display the duty cycle of a laser, the number of pulses, elapsed time, the number of pulses, the average pulse width in µs, and total energy applied. This data can be transmitted digitally via RS485 or Ethernet.

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